Looking for a Non-Hygroscopic Elastomer with Water Absorption Rate Under ISO 62

You want the properties to enhance/ease processing, or for final, molded part?

Are you injection molding these parts?

No real information here to work with.

You may need to contact suppliers and ask them.

All elastomers absorb and transmit water vapor.

For final molded part , injection process , Santoprene 8201-90 , it's Non-hygroscopic , but on their MSDS no water absorption rate , Exxonmobil replied they have no such data for reference , which means they do not take the test via ISO 62 or ASTM D570 .
It is the same as GLS 's low hygroscopic resin G7690-01 ,
If no such date , how can they determine Low or Non hygroscopic ?

Maybe something made from this one?

gotta be thinking outside the box and hook up to some research institutes!

Have you considered Dupont Viton? Expensive. Should work.

http://www.dupontelastomers.com/products/viton/